Method of delivering, transporting, and storing proppant for delivery and use at a well site

ABSTRACT

A method of delivering proppant to a well site has the steps of transporting a load of proppant in a vessel to a desired location, moving the load of proppant from the vessel into a container so as to create a proppant-loaded container, unloading the proppant-loaded container into a pneumatic bulk trailer, and transporting the unloaded proppant in the pneumatic bulk trailer to well site. The container is placed onto a bed of a truck and moved in proximity to the vessel. The proppant-loaded container is placed onto a tilting mechanism and then tilted so that the proppant is discharged through a flow gate of a container into a hopper. The proppant in the hopper can then be conveyed to the pneumatic bulk trailer.

RELATED APPLICATIONS

This application claims the benefit of, is a continuation of, and is aU.S. National Stage of International Patent Appln. No. PCT/US13/32819,filed on Mar. 18, 2013, which claims the benefit of U.S. patentapplication Ser. No. 13/427,140 filed Mar. 22, 2012, now U.S. Pat. No.8,622,251 issued on Jan. 7, 2014, which is a continuation-in-part ofU.S. patent application Ser. No. 13/332,937 filed on Dec. 21, 2011, allof which are incorporated herein by reference in their entireties.

BACKGROUND

1. Field of the Invention

The present invention relates to proppant storage containers. Moreparticularly, the present invention relates to systems and methods forthe delivery of proppant to a well site. More particularly, the presentinvention relates to containers as part of a system of storing proppantprior to delivery to a well site.

2. Description of Related Art

Hydraulic fracturing is the propagation of fractions in a rock layercaused by the presence of pressurized fluid. Hydraulic fractures mayform naturally, in the case of veins or dikes, or may be man-made inorder to release petroleum, natural gas, coal seam gas, or othersubstances for extraction. Fracturing is done from a wellbore drilledinto reservoir rock formations. The energy from the injection of ahighly-pressurized fracturing fluid creates new channels in the rockwhich can increase the extraction rates and ultimate recovery of fossilfuels. The fracture width is typically maintained after the injection byintroducing a proppant into the injected fluid. Proppant is a material,such as grains of sand, ceramic, or other particulates, that prevent thefractures from closing when the injection is stopped.

With the rise of hydraulic fracturing over the past decade, there is asteep climb in proppant demand. Global supplies are currently tight. Thenumber of proppant suppliers worldwide has increased since 2000 from ahandful to well over fifty sand, ceramic proppant and resin-coatproducers.

By the far the dominant proppant is silica sand, made up of ancientweathered quartz, the most common mineral in the Earth's continentalcrust. Unlike common sand, which often feels gritty when rubbed betweenthe fingers, sand used as a proppant tends to roll to the touch as aresult of its round, spherical shape and tightly-graded particledistribution. Sand quality is a function of both deposit and processing.Grain size is critical, as any given proppant must reliably fall withincertain mesh ranges, subject to downhole conditions and completiondesign. Generally, coarser proppant allows the higher flow capacity dueto the larger pore spaces between grains. However, it may break down orcrush more readily under stress due to the relatively fewergrain-to-grain contact points to bear the stress often incurred in deepoil- and gas-bearing formations.

Typically, in any hydraulic fracturing operation, a large amount of suchproppant is required. Typically, it has been difficult to effectivelystore the proppant at the fracturing sites. Additionally, it has beenfound to be rather difficult to effectively transport the proppant tothe desired location. Often, proppant is hauled to the desired locationson the back of trucks and is dumped onsite. Under such circumstances,the proppant is often exposed to adverse weather conditions. This willeffectively degrade the quality of the proppant during its storage.Additionally, the maintenance of proppant in containers at the hydraulicfracturing site requires a large capital investment in storagefacilities. Typically, the unloading of such storage facilities iscarried out on a facility-by-facility basis. As such, there is a need tobe able to effectively transport the proppant to and store the proppantin a desired location adjacent to the hydraulic fracturing location.

Present methods of storing proppant for use at the well site hasinvolved a significant investment in structural facilities. Inparticular, silos have been built in order to store proppant for use inthe fracturing operation. Often, the silos can have a cost of severalmillion dollars. Whenever such silos are used, there is a possibility ofcontamination of the proppant that is contained within the silo. Largestorage facilities often mix various types and qualities of proppant. Assuch, lower quality proppant may be mixed with higher quality proppantso as to create an undesirable contaminated combination.

The availability of high quality proppant is always of a major concernduring such fracturing operations. If the proppant is not available atthe well site, then the fracturing operation can stall until such timethat proppant is available. In other circumstances, the operators of thefracturing operation may be forced to use lower quality proppant inorder to continue the operation. As such, there is a need to be able tohave high quality proppant available at all times during the fracturingoperation. It is also advantageous to provide a system which avoids themixture of different types of proppant and to avoid the contamination ofthe proppant supply.

Under certain circumstances, railcars are used to deliver proppant tothe fracturing location. The proppant is unloaded from the railcars intopneumatic bulk trailers. The pneumatic bulk trailers can then deliverthe proppant to the well site. Often, the bulk materials train will haveto remain on-site during the time the proppant remains in the bulkmaterial train. As such, the train is not able to be used for otherpurposes. This adds additional cost to the fracturing operation.Ultimately, after the train is completely unloaded, a new bulk materialtrain must be transported to the desired location and then serve as astorage facility. As such, a need is developed so as to quickly removeall of the proppant from the bulk material train and to store suchproppant until such time as the proppant is needed.

In the past, various patents have issued relating to storage andtransport facilities. For example, U.S. Patent Publication No.2008/0179054, published on Jul. 31, 2008 to McGough et al., shows a bulkmaterial storage and transportation system. In particular, the storagesystem is mounted on the trailer of a truck. The storage system includeswalls that define an interior volume suitable for receiving theaggregate material therein. There are hoppers provided at the bottom ofthe container. These hoppers have inclined walls. The hoppers can extendso as to allow the material from the inside of the container to beproperly conveyed to a location exterior of the container. Actuators areused so as to expand and collapse the container.

U.S. Pat. No. 7,240,681, issued on Jul. 10, 2007 to L. Saik, describes atrailer-mounted mobile apparatus for dewatering and recovering formationsand. The trailer is mounted to a truck-towable trailer so as to receivesand therein. The container has a pair of sloping end walls. The backend of the container is suitably openable so as to allow the sand to beremoved therefrom. A pneumatic or hydraulic ram is provided on theforward part of the container so as to allow the container to be liftedangularly upwardly so as to allow sand to be discharged through the gateat the rear of the container.

U.S. Pat. No. 4,247,228, issued on Jan. 27, 1981 to Gray et al.,describes a dump truck or trailer with a pneumatic conveyor. Thecontainer is mounted to a frame on wheels. A hydraulic ram tilts thecontainer for dumping through a rear outlet. A pneumatic conveyor iscarried by the frame with an intake at the rear of the container. A gateallows the solids to be dumped conventionally by gravity or to be blownto a storage facility by the pneumatic container. The container has atop hatch formed therein so as to allow the solids to be introduced intothe interior of the container.

U.S. Pat. No. 2,865,521, issued on Dec. 23, 1958 to Fisher et al., showsa bulk material truck that has an interior volume suitable for thereceipt of bulk material therein. A pneumatic conveyer is utilized so asto allow the removal of such material from the bottom of the container.A pair of sloping walls are provided on opposite sides of the containerso as to allow the bulk material within the container to be passedtoward the bottom of the container. A top hatch is provided on the topof the conveyer. The pneumatic conveyer is connected to the bottom ofthe container.

U.S. Pat. No. 4,995,522, issued on Feb. 26, 1991, to F. M. Barr,describes a bottom dumping bulk container apparatus for a bulkgranulated material. The shipping container has a lower wall with adischarge opening. Doors are provided for the opening and closing of thedischarge opening. The doors are actuated by an actuating structurewhich is mounted for vertical movement relative to the container. Theactuating structure has upper portions which serve as conventionallifting connectors or receptacles at corners of the container. Thesecooperate with conventional hooks so that raising the actuatingstructure opens the door and lowering the actuating structure closes thedoor. This permits granulated material within the container to be dumpedinto a lower container or conveyance without requiring specializedlifting or opening equipment.

U.S. Pat. No. 6,401,983, issued on Jun. 11, 2002 to McDonald et al.,provides a bulk cargo container for storing and transporting solid andliquid bulk materials. The bulk cargo container includes a vesselsuitable for containing the bulk material and a supporting frameassembly having a generally horizontally-disposed support memberattachment. The container portion is formed into at least one hopperhaving a discharge opening therein suitable for discharging bulkmaterial contained within the vessel.

U.S. Pat. No. 4,138,163, issued on Feb. 6, 1979 to Calvert et al.,discloses a bulk material container for the handling of flowableparticulate materials. This container has a closed, generallyrectangular parallelpiped structure with side walls, end walls and aroof. Conduits permit the introduction and withdrawal of particulatematerial to and from the container body. The lower base portion supportsa vertical flexure panel at each corner thereof. The vertical flexurepanel supports opposed pairs of longitudinal and transverse flexurepanels between the tops thereof.

U.S. Pat. No. 4,909,556, issued on Mar. 20, 1990 to T. Koskinen,provides a transport container for the transport of bulk material. Thistransport container has a filling-hole in the upper part and an emptyingdevice in the rear. For the loading and unloading, a side section isprovided that can be opened. An emptying device, in the nature of apneumatic pressure discharger, allows the material to freely flow fromthe containers through a check valve.

U.S. Pat. No. 7,967,161, issued on Jun. 28, 2011 to A. M. Townsend,provides a shipping container liner system for the shipping of bulkflowable materials. The system has a specially-adapted shippingcontainer liner that is self-supporting without the need forrear-mounted rigid supportive bars to retain the liner within theshipping container during filling and discharge. The system has anarrangement of interior support baffles operating in conjunction with aplurality of exterior anchor straps adapted to distribute the cargo loadthroughout the length of the container.

U.S. Pat. No. 5,690,466, issued on Nov. 25, 1997 to Gaddis et al., showsslope plate for a particulate material truck box. The slope plateassembly includes a plurality of slope plate sections pivotallyconnected to the opposite side walls of the truck box so as to bemovable between a raised inoperative position and a lowered operativeposition. In the lowered position, particulate material flows by gravityalong the slope plate sections for discharge into an auger assemblyresiding below the floor of the truck box. In the raised position, bulkmaterial or other cargo can be loaded into the truck box.

It is the object of the present invention to provide a system for thestorage and transport of proppant that is mobile, scalable and flexible.

Another object to the present invention to provide a system for thestorage and transport of proppant that can be located in proximity tothe rail spur.

Another object of the present invention to provide a system for thetransport and storage of proppant that can be rapidly implemented.

Another object of the present invention to provide a system for thestorage and transport of proppant that occupies a small footprint.

The further object of the present invention to provide a system for thestorage and transport of proppant that assures a continuous inventory ofproppant to the fracturing operation.

Still another object of the present invention is to provide a system forthe storage and transport of proppant that is movable and rechargeableat the drill site.

The further object of the present invention is to provide a system forthe storage and transport of proppant that enhances the productivity ofthe proppant supplier.

The further object of the present invention to provide a system for thestorage and transport of proppant that reduces driver fatigue.

Another object of the present invention to provide a system for thestorage and transport of proppant that reduces liabilities.

The further object of the present invention to provide a system for thestorage and transport of proppant that improves safety.

Further object of the present invention to provide a system for thestorage and transport of proppant that is compliant with Department ofTransportation regulations.

Still another object of the present invention to provide a system forthe storage and transport of proppant which improves the profits for theproppant supplier.

These and other objects and advantages of the present invention willbecome apparent from a reading of the attached specification andappended claims.

SUMMARY

The present invention is an apparatus for proppant storage. Thisapparatus comprises a container having a bottom wall, a top wall, a pairof side walls, and a pair of end walls. The pair of side walls extendbetween the pair of end walls and between the bottom wall and the topwall. The container has an interior volume. A hatch is positioned on thetop wall. This hatch is openable so as to allow the proppant to beintroduced into the interior volume of the container. A flow gate ispositioned on one of the end walls. The flow gate is openable so as toallow the proppant to flow outwardly of the interior volume of thecontainer.

In the apparatus of the present invention, at least one of the end wallsis recessed inwardly of the end of the pair of side walls and inwardlyat the bottom wall and inwardly at the top wall. This end wall has agenerally convex shape. A proppant inlet is affixed to the end wall. Theproppant inlet communicates with the interior volume of the container.The proppant inlet is suitable for allowing proppant to be introducedinto the interior volume of the container. A vent also opens to theinterior volume. This vent is formed at an upper portion of one of thepair of end walls.

A longitudinal member is positioned in the interior volume of thecontainer. The longitudinal member has one end affixed to one of thepair of end walls and an opposite end affixed to the other of the pairof end walls. A first cross member is positioned in the interior volumeof the container. The first cross member has one end affixed to one ofthe pair of side walls and an opposite end affixed to the other of thepair of side walls. A second cross member is positioned in the interiorvolume of the container and in spaced relationship to the first crossmember. The second cross member has one end affixed to one of the pairof side walls and an opposite end affixed to the other of the pair ofside walls. A flow gate is positioned on one of the end walls generallyadjacent to the bottom, wall. This flow gate is slidable between an openposition and a closed position.

The present invention is also a method of delivering proppant thatcomprises the steps of: (1) transporting a load of proppant in a vesselto a desired location; (2) moving the load of proppant from the vesselinto a container so as to create a proppant-loaded container; (3)unloading the proppant-loaded container into a pneumatic bulk trailer;and (4) transporting the unloaded proppant in the pneumatic bulk trailerto a well site.

The vessel is a hopper of a bulk material train. The step oftransporting includes loading the hopper with proppant in a remotelocation and then transporting the loaded proppant in the hopper of thebulk material train to the desired location. The step of moving includesconveying the proppant from the hopper of the bulk material train into ahatch formed at the top of the container.

The container can be placed onto the bed of a truck. The truck is movedso that the container is adjacent to the vessel. As such, the emptycontainer is available so that the proppant can be conveyed from thehopper of the bulk material train into the interior volume of thecontainer.

The step of unloading includes placing the proppant-loaded containeronto a tilting mechanism, tilting the placed proppant-loaded containerto an angle such that an end wall of the container faced downwardly atan angle, and discharging the proppant from the tilted container to aflow gate of the container. The proppant flows through the container ofthe flow gate into a hopper. This flowed proppant is conveyed from thehopper into the pneumatic bulk trailer. Air is injected into thecontainer as the proppant flows through the flow gate. A plurality ofthe proppant-loaded containers can be stacked at the desired locationprior to the step of unloading.

The present invention is also a method of delivering and storingproppant for use at the well site. This method includes the steps of:(1) transporting the load of proppant in a vessel to a desired location;(2) moving the load of proppant from the vessel into a plurality ofcontainers so as to create a plurality of proppant-loaded containers;(3) stacking the plurality of proppant-loaded containers at the desiredlocation so as to form a stack of the proppant-loaded containers; (4)lifting an upper most proppant-loaded container from the stack; (5)moving the upper most proppant-loaded container to a tilting mechanism;and (6) tilting the proppant-loaded container by the tilting mechanismso as to discharge the proppant from the container.

The discharged container can be transported to another stack of emptycontainers or to a position adjacent to the proppant-containing vessel.The proppant is discharged to a flow gate of the tilted proppant-loadedcontainer into a hopper. The proppant from the hopper can be conveyedinto a pneumatic bulk loader. The transported conveyed proppant in thepneumatic bulk trailer can then be transported to the well site.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prospective view of the container apparatus as used in thesystem of the present invention.

FIG. 2 is an end view of the container apparatus as used in the systemof the present invention.

FIG. 3 is an illustration of the system of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown the proppant storage apparatus 10 inaccordance with the preferred embodiment of the present invention. Theproppant storage apparatus 10 includes a container 12 having a bottomwall 14, a top wall 16, a pair of side walls 18 and 20 and a pair of endwalls 22 and 24. The side wall 18 extends between the bottom wall 14 andthe top wall 16. The side wall 20 also extends between the bottom wall14 and the top wall 16 in generally spaced parallel relationship to theside wall 18. The end wall 22 extends between the bottom wall 14 and thetop wall 16. Similarly, the end wall 24 extends between the bottom wall14 and the top wall 16 and also between the side walls 18 and 20. Thetop wall 16 has a hatch 26 formed thereon. Hatch 26 is openable so as toallow proppant to be introduced into the interior volume of thecontainer 12. A flow gate 28 is positioned on the end wall 22. The flowgate 28 is openable so as to allow the proppant to flow outwardly of theinterior volume of the container 12.

It can be seen that the end wall 22 is recessed inwardly of an end ofthe pair of side walls 18 and 20 and inwardly of the bottom wall 14 andthe top wall 16. As such, the outermost end 30 of the container 12 willprovide a protective structure for the generally convex surface of theend wall 22. This convex shape of the end wall 22 facilitates theability to funnel the proppant from within the interior volume ofcontainer 12 outwardly through the flow gate 28. The frame structure atthe end 30 enhances the structural integrity of the container 12 at thisend while protecting the mechanical structures associated with the flowgate 28. The flow gate 28 is slidable upwardly so as to open to theinterior volume. An inlet 32 is generally positioned at the end wall 22and opened through the end wall 22 to the interior volume of thecontainer 12. This proppant inlet is suitable for allowing proppantand/or air to be introduced into the interior volume of the container.As such, when the container 12 is at a well site or other location,additional proppant can be introduced into the interior volume of thecontainer 12 through the proppant inlet 32. Inlet 32 also allows air tobe introduced into the interior volume of the container 12 so asfacilitate the ability of the proppant within the container 12 to exitthrough the flow gate 28. The inlet 32 is in the nature of a tube thatcan be connected to a suitable hose. A vent 34 is also positioned at theend wall 22. Vent 34 opens to the interior volume of the container 12 soas to allow excess air pressure to exit outwardly of the container 18.

The container 10 is configured so as to contain 96,000 pounds ofproppant therein. Since each railcar can transport 192,000 pounds ofproppant, a pair of containers 12 can receive all of the proppant fromthe railcar. However, conventional shipping containers could lack thestructural integrity to contain such a large weight. As such, theproppant storage apparatus 10 includes an interior structure whichenhances the integrity of the container 12 for its intended purpose.

In particular, a longitudinal member 36 is positioned in the interiorvolume of the container 12. Longitudinal member 36 extends generallycentrally of the interior volume of the container 12. The longitudinalmember 36 has one end rigidly affixed to the end wall 22 and an oppositeend rigidly affixed to the end wall 24. This connection will maintainthe integrity of the end walls 22 and 24 in spite of the large weight ofproppant urging thereagainst. A first cross member 38 is positionedwithin the interior volume of the container 12. The first cross member38 has one end affixed to the side wall 18 and an opposite end affixedto the side wall 20. A second cross member 40 is also positioned in theinterior volume of the container and is in generally spaced parallelrelationship to the first cross member 38. Each of the cross members 38and 40 is positioned generally centrally with respect to the height ofthe container 12. The second cross member has one end affixed to theside wall 18 and an opposite end affixed to the side wall 22. The crossmember 38 and 40 are configured so as to maintain the, integrity of theside walls 18 and 20 against the large weight of proppant containedwithin the interior volume of the container 12.

FIG. 2 is an end view showing the proppant storage apparatus 10 of thepresent invention. In particular, the end wall 22 of the container 12 isillustrated as having a hatch 28 slidably received within guides 42thereon. Suitable hydraulic or pneumatic mechanisms can be associatedwith the flow gate 28 so as to raise or lower the flow gate 28. In thelowered position, the flow gate 28 locks the flow of proppant from theinterior volume of the container 12. In the raised position, the flowgate 28 will open to the interior volume of the container 12 so as toallow proppant to be discharged therefrom. The proppant inlet 32 and thevent 34 are illustrated as positioned on the end wall 22.

Within the concept of the present invention, it is advantageous to beable to stack several containers on top of one another. As such, the endsurface 30 has structural uprights 44 and 46 thereon. Similarly,horizontal structural members 48 and 50 will extend between thestructural uprights 44 and 46 at the top and bottom of the container 12.The structural members enhance the integrity of the container so that alarge amount of weight can be stacked upon the container 12. Again, thestructural members 44, 46, 48 and 50 enhance the integrity of thecontainer 12 to the heavy weight supported therein.

FIG. 3 shows a system 60 of the present invention. The system 60initially involves the transport of a load of proppant to a desiredlocation in a vessel 62. The vessel 62 is in the nature of hoppersassociated with a bulk material train 64. The bulk material train 64 isdriven by an engine 66 located on a rail spur 68. As such, in thepresent invention, the bulk material is delivered by the bulk materialtrain 64 to the desired location. The vessel 62 of the bulk materialtrain 64 can be immediately unloaded at this desired location so thatthe engine 66 can return the bulk material train 64 for other railroadusages.

The rail spur 68 is illustrated as being located in an elevatedlocation. As such, containers 70, 72, 74 and 76 can be located inproximity to the vessel 62 and adjacent to the bulk material train 64.Each of the containers 70, 72, 74 and 76 has a configuration similar tothat shown herein in association with FIGS. 1 and 2.

The hatch on the top wall 78 of the container 70 is illustrated as beingadjacent to a conveyer 80 associated with the vessel 62. In other words,the hopper of the bulk material train 64 is opened adjacent to theconveyer 80. The conveyer 80 extends between the gate of the vessel 62and the hatch at the top wall 78 of the container 70. Once this hopperof the bulk material train 64 is unloaded into the vessel 70, theconveyer 80 can be moved forwardly along the bulk material train 64 sothat another hopper can discharge its proppant content into thecontainer 72 of truck 82. The containers 70 and 72 are supported on thebed of the truck 82. Similarly, a conveyer 84 allows the unloading ofanother hopper of the bulk material train 64 into the container 74. Thecontainer 76 can be maintained in proximity to another hopper of thebulk material train 64 so that further unloading can occur.

A container loader/unloader 86 is positioned so as to allow for thelifting and transport of the containers 70, 72, 74 and 76. Inparticular, in FIG. 3, in can be seen that the container loader/unloader86 has removed the containers from the truck 88 and has placedcontainers 92 and 92 upon tilting mechanisms 94 and 96, respectively.The tilting mechanisms 94 and 96 include a support panel that ispivotally connected to a frame. A hydraulic mechanism can then pivot theplate upwardly so that the container 90 is tilted so that the end wallfaces at an angle downwardly toward a hopper 98. The tilting mechanism96 also includes a similar structure such that the end wall of thecontainer 92 is directed downwardly toward the hopper 100. The tiltingmechanisms 94 and 96 allow proppant to be discharged in a very fast,convenient and safe manner into the respective hoppers 98 and 100.

A conveyer 102 extends to the bottom of the hopper 98 and to the top ofa pneumatic bulk trailer 104. As a result, the proppant that isdischarged through the flow gate at the end wall of the container 92into the hopper 98 is transported by the conveyer 102 into the pneumaticbulk trailer 104. Similarly, another conveyer 106 extends from thehopper 100 to another pneumatic bulk trailer 108 so as to dischargeproppant into the pneumatic bulk trailer. When each of the pneumaticbulk trailers 108 has been filled with proppant, these pneumatic bulktrailers 104 and 108 can then transport the proppant to the well site.

Flatbed trucks 110 and 112 are in line for receiving additionalcontainers 114. Truck 112 is positioned adjacent to the container 114 sothat the container loader/unloader 116 can place the containers onto theflatbed of the truck 112. Truck 112 can then move to another positionadjacent to the bulk material train 64 for the further unloading of thehoppers associated therewith. As such, it can be seen that the stagingof the various flatbed trucks allows for the efficient and effectiveremoval of the proppant from the hoppers of the bulk material train 64.

In FIG. 3, the containers 114 are arranged in a stacked configuration.The containers 114, as illustrated in FIG. 3, are stacked in a five-highstack since the containers are empty. However, within the concept of thepresent invention, if it is possible to unload the bulk material train64 faster than the bulk material trailers 104 and 108 are available,then the filled containers can also be arranged in a stack. Typically,the containers can only be stacked four-high in view of large weightsupported therein. These containers can be stacked until such time asproppant is required or until such time as equipment is available forthe unloading of such containers.

Each of containers as utilized in the system of the present invention isa specially designed 8 foot by 20 foot container that is capable ofcontaining 96,000 pounds of proppant. The containers can be moved byflatbed, low bed and container chassis that are accessible andeconomical. The facilities, such as illustrated in FIG. 3, requires only1.5 acres to manage 45 million pounds of proppant. Empty containers canbe stacked five-high and full containers can be stacked three or fourhigh. Lashing can be used to ensure safety. The containers associatedwith the present invention allow proppant to be removed in an efficientand effective manner. Air can be injected through the inlet so as tofacilitate the flow of proppant outwardly at the flow gate. In thisarrangement, it has been found that 90,000 pounds of proppant can beunloaded in fifteen minutes.

Each of the containers can be arranged as to store 360,000 pounds ofproppant per 160 square feet of footprint. The unloading equipment canunload one railcar in less than twenty minutes or unload a 120 car unittrain in less than 48 hours. Multiple railcars can be unloaded at thesame time.

The arrangement of containers is scalable for as much or as littleproppant as required. A WMS inventory control system can be utilized. Insuch a system, each container can be bar-coded and logged-in to trackthe amount of proppant on hand by the mesh size of the proppant. Oncethe containers are loaded, they can be easily and safely stacked up inyards. As such, air space is utilized as opposed to yard space. All thatis required is a solid foundation and proper container handlingequipment.

The proppant is unloaded from containers to pneumatic bulk trailers. Assuch, the proppant will stay dry and would be manipulated less thenflat-stored proppant. When the proppant is ordered, the container-movingmachines move the container to hydraulic chassis. Proppant is thendumped into the hoppers. An airbox is utilized so as to blow theproppant out of the container.

The process of the present invention ensures close proximity of the siteto the rail spur. The process of the present invention can be rapidlyimplemented when compared to silo facilities. Typically, such silofacilities can take up to two years to build. The number of containersis scalable for inventory requirements. A mini-stack of containers canbe moved and recharged at the drill site so as to ensure continuousinventory for the fracturing operation. The system of the presentinvention can move the inventory closer to the production field then theprior art.

The present invention provides a lower overall cost per ton of proppant.In particular, the empty containers can be staged on-site at the mine.This serves to smooth out productivity for the proppant supplier. Italso serves to improve throughput/profits for the proppant supplier. Anyover supplies or leftover production can be stored on-site. This allowsthe company to negotiate better rates in exchange for helping theproppant supplier with their supply chain problems.

In contrast to prior systems where the pneumatic bulk trailercontinually moves back and forth from the bulk material train to thewell site, the present invention allows for the storage of such proppantin a location adjacent to the rail line. As a result, the truck driverscan have reduced fatigue. A safer work environment is promoted by thesystem of the present invention. A higher quality driver pool ismaintained. Additionally, this system complies with Department ofTransportation regulations.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof. Various changes in the details ofthe illustrated construction can be made within the scope of theappended claims without departing from the true spirit of the invention.The present invention should only be limited by the following claims andtheir legal equivalents.

That claimed is:
 1. A method of transporting proppant, the methodcomprising: a) vertically stacking a plurality of empty proppantcontainers in close proximity to a rail spur so that one of theplurality of empty proppant containers overlies another one of theplurality of empty containers thereby to reduce footprint of the arearequired adjacent the rail spur to store the plurality of empty proppantcontainers, each of the plurality of empty containers including at leasta first end surface and at least a second different end surface and eachof the first and second end surfaces having a plurality of uprightstructural support members thereon to enhance integrity of the containerso that a large amount of weight can be stacked upon the container andso that heavy weight can be stored therein; b) filling the plurality ofempty proppant containers with proppant from one or more proppanttransporting rail vehicles thereby to produce a plurality of proppantfilled containers; c) transferring the plurality of proppant filledcontainers with a loader onto one or more support platforms associatedwith one or more proppant transporting road vehicles.
 2. The method ofclaim 1, wherein the plurality of proppant filled containers comprises afirst plurality of proppant filled containers, and the method furthercomprising: filling a second plurality of empty proppant containers withproppant from one or more proppant transporting rail vehicles thereby toproduce a second plurality of proppant filled containers: and verticallystacking the second plurality of proppant filled containers with aloader so that one of the plurality of proppant filled containersoverlies another one of the plurality of filled containers to reduce thefootprint of the area required for storage of the proppant in closeproximity to the rail spur.
 3. The method of claim 1, wherein thesupport platform is a tiltable support platform, the method furthercomprising: tilting the support platform and one or more of theplurality of proppant filled containers located on the platform todischarge proppant from an opening adjacent an end of the one or more ofthe plurality of proppant filled containers.
 4. The method of claim 1,further comprising: conveying the proppant from the one or more proppanttransporting rail vehicles to the plurality of empty proppant containerson a first conveyor; and conveying the proppant from one or more of theplurality of proppant tilled containers to one or more proppanttransporting road vehicles on a second conveyor.
 5. The method of claim4, further comprising: channeling the proppant from the plurality ofproppant tilled containers to the second conveyor through a hopper. 6.The method of claim 1, further comprising: moving the plurality of emptyproppant containers from the storage location, to the one or moreproppant transporting rail vehicles and then to the one or more supportplatforms located on the one or more proppant transporting roadvehicles.
 7. The method of 1, wherein the one or more proppanttransporting road vehicles comprises a plurality of proppanttransporting road vehicles, and wherein the method further comprises:staging the plurality of proppant transporting road vehicles so thateach of the plurality of proppant transporting road vehicles receivesone or more of the plurality of proppant filled containers, delivers thecontainer away from the one or more proppant transporting rail vehicles,thereby increasing the efficiency with which proppant is transferredfrom the one or more proppant transporting rail vehicles to theplurality of proppant transporting road vehicles.
 8. The method of claim1, wherein step b) further comprises: discharging the proppant from theone or more proppant transporting rail vehicles onto a conveyor; andconveying the proppant on the conveyor from the proppant transportingrail vehicle to an inlet in each of the plurality of empty proppantcontainers.
 9. The method of claim 1 further comprising: aftertransferring the plurality of proppant filled containers to the one ormore support platforms associated with the one or more proppanttransporting road vehicles, returning another plurality of emptyproppant containers to the proppant transporting rail vehicle to befilled proppant.
 10. The method of claim 1, further comprising:positioning a conveyor proximate a proppant transporting rail vehicle toreceive proppant from the proppant transporting rail vehicle and therebyconvey the proppant away from the proppant transporting rail vehiclewhen the conveyor operates; positioning the plurality of empty proppantcontainers to receive proppant from the conveyor sequentially so that asone of the plurality of empty proppant containers is filled to a desiredlevel, such one container then being removed in favor of another one ofthe plurality of empty proppant containers with the capacity to acceptmore proppant; after removal of proppant from the conveyor, transportingeach of the plurality of proppant tilled containers away from theproppant transporting rail vehicle.
 11. The method of claim 10, furthercomprising: loading each of the plurality of proppant tilled containersonto a tillable platform; providing a conveyor between the tiltableplatform and one or more proppant transporting road vehicles; andtilting the platform to discharge the proppant from the container intothe conveyor.